1. Field of the Invention
The present invention relates to a method of deriving a parking trajectory for a vehicle, which derives a parking trajectory based on a reversing linear path within an angle of the radius of rotation for parking, thus improving convenience and reducing the complexity of calculation.
2. Description of the Related Art
Automatic parking systems (auto parking system) have begun to be installed in vehicles as an aide for drivers who ordinarily have a difficult time their car. In conventional auto-parking systems, a driver identifies the location of an obstacle using a camera or an ultrasonic sensor attached to the rear of a vehicle when parking the vehicle. When the driver selects parallel parking or perpendicular parking, the auto-parking system performs a relevant operations required to park the individuals vehicle.
Ordinarily, a camera is installed in such conventional auto-parking systems and is configured to provide the driver is a real time display of the area behind, next to or even in front of the vehicle. Based on the view in the camera, the driver selects a parking space identified by the camera and the auto-parking system automatically controls the steering wheel of the vehicle using sensor values from a plurality of sensors installed around the outer peripheral of the vehicle, thus enabling the vehicle to be safely parked.
FIG. 1 is a diagram illustrating a parking trajectory utilized by a conventional auto-parking system to parallel park a vehicle. In this conventional trajectory calculation, the auto-parking system utilizes a trajectory based on a minimum radius of rotation, and thus the vehicle is turning with a radius R1 around point C to enter the parking space.
Accordingly, the conventional auto-parking system must form a parking trajectory using a formula based on a tangential line between a rotating circle forming the minimum radius of rotation along the trajectory and a straight line when parallel parking a vehicle. However, in order to form a parking trajectory in the form of a continuous trajectory when parallel parking, a steering motor operating the steering wheel must generate a square wave operating signal. However, it is quite difficult for the steering motor to accurately generate this type of square wave operating signal. Thus, as shown in FIG. 2, a certain degree of error exits thereby reducing the effective parking performance of the system.
FIG. 3 is a diagram showing one solution that has been proposed to reduce the error output by the steering motor. In particular, a steering angle is calculated using a trajectory formula required to park a vehicle, and a motor is rotated forwards or backwards at a predetermined angle in compliance with a command signal output from a control unit, so that a parking trajectory satisfying a continuous range for a steering angle is formed, thus reducing an error between a designated ideal parking trajectory and an actual parking trajectory.
However in this solution, the procedure for deriving a trajectory is relatively complicated, thus making it inefficient to calculate parking trajectory of a vehicle in various conditions. Thus, the device in the proposed solution above is not scalable to a multiple different parking situations which a driver may typically encounter in, e.g., a city.
The foregoing is intended merely to aid in the better understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.